Automatic paster control for rotarypress printing plants



Jan. 2, 1962 E. J. FLANNERY ETAL 3,015,454

AUTOMATIC FASTER CONTROL FOR ROTARY-PRESS PRINTING PLANTS Filed March 29, 1960 4 Sheets-Sheet 1 B H A H H M w. W P d 4/5 W OP W W 0 0/ 0 U 0 0 0 C 0 0 0 0 m 2 900 L 0' A I E 9 m E H C W m T E M n 0 a P IA 8 FIG.

Ja 2, 1962 E. J. FLANNERY ETAL 3,015,454

AUTOMATIC FASTER CONTROL. FOR ROTARYPRESS PRINTING PLANTS Filed March 29, 1960 4 Sheets-Sheet 2 VOL T5 Jan. 2, 1962 E. J. FLANNERY EI'AL 3,015,454

ESS PRINTING PLANTS AUTOMATIC FASTER CONTROL FOR ROTARY-PR Filed March 29, 1960 4 Sheets-Sheet 3' Jan. 2, 1962 E. J. FLANNERY ETAL 3,015,454

AUTOMATIC FASTER CONTROL FOR ROTARY-PRESS PRINTING PLANTS Filed March 29, 1960 4 Sheets-Sheet 4 3,015,454 AUTDMATTC PASTER CONTROL FOR ROTARY- PRESS PRINTING PLANTS Edward .3. Fiannery, Chicago, and Francis A. Raymond, La Gran e, Ill, assignors to R. Hoe & Co., Inc., New York, N.Y., a corporation of New York Filed Mar. 29, 1960, Ser. No. 18,300 8 Claims. (Cl. 242-582) Our invention relates to rotary-press printing plants and particularly to an electric system for automatically controlling the paster or splice-making equipment WLliCh attaches the web of a new roll of paper to that of an expiring roll during continuous operation of the press.

For such splicing, the new roll of paper is first prepared by attaching the leading edge of the paper web to the next wrap by means of adhesive tabs, and thereafter applying an adhesive along strip shaped areas across the web end. Preferably, the adhesive strip areas are normally dry and are subsequently activated after the new roll of paper is mounted on the roll stand and just about to be spliced to the web of the expiring roll.

When the prepared roll is mounted on the reel stand, and before making a splice, the roll is first shifted to a position close to the web still passing from the expiring roll to the rotary press. At the proper time, the new roll is accelerated up to a peripheral speed equal to the travelling speed of the expiring web. According to the wet glue method, the above-mentioned adhesive areas are activated before the new roll is thus accelerated, and the expiring web is placed into contact with the wet adhesive by deflector brushes when speed equality is reached. According to the dry glue method, a solvent is brushed or sprayed onto the surface of the new roll thus activating the adhesive, this being done when speed equality is attained. in both cases, the web end of the new roll is thus spliced to the expiring web, the above-mentioned tabs are torn, and the web of the new roll is entrained toward the printing press which continues operating at its normal speed. Shortly thereafter, a tail cutter severs the expiring web from the remainder of the depleted roll which can then be removed from the reel stand to be replaced by another, new roll.

For economical operation, particularly in a newspaper printing plant where the operating speed may be 20,000 to 60,000 impressions per hour (IPH) or more, corresponding to a linear web-travel speed of about 500 to 2,000 feet per minute, it is essential that the above-described operation of the paster be made and completed at the proper time. If the splice is made too late and hence on too small a diameter, the performance is unreliable. If the splice is made too early, a considerable amount of paper is wasted on the depleted roll. It has become known, therefore, to control the paster operation by having the attendant actuate a push-button which initiates the paster operation by first shifting the new roll of paper to proper position, and moving the above-mentioned activating device, such as a brush or sprayer, as well as the tail cutter into active position (first portion of paster cycle), whereafter the paster means proper, such as the brush, as well as the tail cutter, are tripped to operate in timed sequence (second portion of paster cycle). The known control systems of this type, however, leave much to be desired for the reasons explained presently.

As mentioned, the first portion of the paster cycle, commencing after the new roll is in ready position, comprises the steps of positioning the splice-making and tail cutter devices. The time needed for these initial operations is substantially constant and may amount to 10 seconds, for

hired States Patent "ice example. Thereafter the new roll of paper must be accelerated so that its peripheral speed is equal to the linear travel speed of the expiring web. The period of time needed for this purpose is not constant but depends upon the speed of the printing press. For example, the roll acceleration time may be 15 seconds for a press speed of 20,000 impressions per hour (IPH), 30 seconds for 40,000 IPH, and 45 seconds for 60,000 IPH. The time allowed for the second portion of the paster cycle, namely the splicing operation proper, is substantially constant and may amount to 10 seconds regardless of the press speed. Referring to the just mentioned examples of numerical values, it follows that the total time for a complete paster operation is 35 seconds for 20,000 IPH, 50 seconds for 40,000 IPH and 65 seconds for 60,000 IPH.

These time values permit a conclusion as to the particular diameter of the expiring roll at which the paster operation is most favorably initiated, as will be explained with reference to FIG. 1 of the drawing, showing the available total time in minutes (coordinate) versus the expiring roll diameter (abscissa) in inches. It will be noted that for a total time of paster operation amounting to 35 seconds at a speed of 20,000 IPH the ideal roll diameter for commencing the paster cycle is 5.5 inches. Accordingly for a web speed of 40,000 IPH and a total operating time of 50 seconds the most favorable roll diameter is 8.25 inches; and at 60,000 IPH the total operating time of 65 seconds corresponds to a most favorable roll diameter of 10.8 inches. The ideal curve indicating the most favorable roll diameters for speeds between 10,000 and 60,000 IPH is indicated in FIG. 1 by A.

It will be recognized that control systems which automatically initiate the paster operation in dependence upon the depleting roll declining to a given initiating diameter, are inadequate to operate economically at the various press speeds.

If the rotating speed of the expiring roll, which increases with declining roll diameter, is taken as a means for initiating the paster cycle, by providing a corresponding tachometer vo'tage and comparing it with a fixed volt age, the results are somewhat better but still inadequate because the most favorable diameter of the expiring roll at which t e initiation of the paster cycle will secure uniformly economical results also depends upon the abovementioned fixed time intervals that are independent of the ro'l diameter or web speed. For example, if on the basis of the numerical example mentioned above, a control system operating in dependence upon a given maximum speed of the expiring roll initiates the paster cycle at a roll diameter of 5.5 inches, the system would initiate the paster cycle at a diameter of 11.0 inches for a web speed of 40,000 IPH, and at a diameter of 16.5 inches for a web speed of 60,000 IPH. These diameter values correspond to the curve B in FIG. 1; and it will be recognized that these diameter vaues, if economical at low speed for securing reliable performance, are increasingly uneconomical toward higher speeds so that considerable waste of paper is involved at web speeds above the minimum speed to which the system is adjusted.

It is an object of our invention to devise a paster control system which automatically secures or closely approaches the ideal performance, irrespective of the press speed, in the sense apparent from the foregoing, thus greatly improving the reliabi'ity and/or economy over the paster control systems heretofore available.

Another object of our invention is to achieve such results with a control system of relatively simple design which requires merely the initiating actuation of a single contact by the attendant or by an automatic sensing means such as a photocell, for thereafter causing the control system to initiate and program the paster operation, at the most favorable time and in the desired timing sequence, until the splice is completed.

To achieve these objects, and in accordance with a feature of our invention, we provide the reel stand with a spindle tachometer or other speed-responsive source of variable pilot voltage proportional to the rotating speed of the expiring roll, and we provide the printing press with a reference tachometer or other source of speed reference voltage proportional to the rotary speed of the press and hence to the travelling speed of the paper web. We connect the two speed-responsive voltage sources to the respective two input circuits of a ratio detector which is controllingly connected to the above-mentioned splicemaking devices in order to release their operation in response to a given ratio of the respective effects imposed upon the ratio detector by said two voltages.

According to another, preferred feature of our invention, we provide the above described source-and-detector circuitry with voltage or current limiting means which are inactive at low press speeds and become active or increasingly active to reduce the effect of the press speed voltage upon the ratio detection in response to that voltage exceeding a given value.

According to other features of our invention, the abovementioned ratio detector is preferaby constituted by a differential relay whose two opposingly acting control coils or control circuits are connected to, and energized from, two dynamoelectn'c tachometer generators driven from the press and on the roll-stand spindle respectively, so that the relay will respond to occurrence of a given difference of the currents flowing in the respective coils or relay control circuits. Furthermore, a value-action rectifier, such as a solid-state diode, is connected parallel to the speed reference tachometer and is poled for limiting the current in one of the coil or control circuits of the relay when the press-speed voltage exceeds a given threshold value. The relay is connected with the above-mentioned splice-making means for tripping these means to make the splice when the dilferential relay responds. The tachometers, of course, need not necessarily be of the dynamo type but may consist of any speed responsive source of voltage, and the relay means may also consist of electronic or semiconductor relay or switching devices capable of responding to a given differential value or ratio.

The foregoing and other objects, advantages and features of our invention, said features being set forth with particuarity in the claims annexed hereto, will be apparent from, and will be mentioned in, the following with reference to the embodiments of control systems according to the invention illustrated by way of example on the drawing in which:

FIG. 1 already discussed, is an explanatory time-versusdiameter diagram.

FIG. 2 illustrates schematically a substantially conventional printing press with an appertaining reel stand and splice-making accessories, as well as some of the components that form part of, or cooperate with, a paster control system according to the invention; FIG. 3 is a schematic circuit diagram of the automatic paster control system; and FIG. 4 is an explanatory graph relating to the same control system.

FIGS. 5 to are the schematic circuit diagrams of six different modifications relating to the ratio-detector or differential-relay portion of a printing press control system otherwise similar to that shown in the preceding illustrations.

The plant ilustrated in FIG. 2 comprises a rotary printing press P which, for the purpose of the present invention, is provided with a reference tachometer PRT. Mounted beneath the press is a reel stand RS whose frame structure 1 carries a rotatable spider assembly 2 with three uniformly distributed reel spindles each of which is provided with a spindle tachometer such as the one denoted by SPT. The spider assembly 2 is shown to accommodate a roll 3 of newsprint just supplying paper to the printing press. Another roll of paper 4 is mounted on a second spindle of the spider assembly and is already prepared for splicing in the manner described above. The third spindle of the spider assembly is vacant and available for mounting thereupon another new roll of paper.

The web 5 of paper passes from the expiring roll 3 over guide rollers 6, 7, 8 and a floating roller 9 to the printing press P. The floating roller is pivotally mounted at 16 and is weighted in accordance with a desired tension to be maintained in the web 5. The web is kept under tension by metal straps 11 which are anchored to the frame structure 1 of the reel stand and kept taut by means of a torque motor 12. Motor 12 is controlled in dependence upon deflecting motion of the floating roller 9, such control being conventional and not further described herein because irrelevant to the present invention proper.

Located above the new roll 4 is an accelerating drive which, in the illustrated embodiment, comprises two rollers 13, 14 and an endless belt 15. The belt assembly is pivotally movable about the axis of roller 14 and is shown disengaged from the roll 4. Prior to making a splice, that is during the first portion of the paster cycle, the accelerating drive is lowered into engagement with roll 4 and is then driven by a motor AM whose control system ADC operates to accelerate the drive until the peripheral speed of roll 4 is equal to the linear speed of the travelling web 5. For this purpose, the control system ADC is operated in dependence upon the press speed by control means not further shown or described herein because known and not essential to the invention proper. The lowering of the accelerating drive 13, 14, 15 is effected by a positioning motor or hydraulic actuator which may be controlled by a positioning contol system PMC in parallel relation to, and in timed sequence with, the positioning motor PM described below.

The accelerating operation just described takes place after the spider assembly 2 is turned clockwise into a position where the roll 4 is close to the expiring web 5. Such rotation is imparted to the spider 2 by a reel rotating motor RM which is stopped under control by a photoelectric cell 16 as soon as the roll 4 reaches the proper position in which the accelerating drive becomes cfiective and thereafter the splice is made.

The plant is further provided with a pastcr assembly 17 which is shown to comprise a brush B and a knife K. Both are normally in respective inactive positions and, during the first portion of the paster cycle, are placed in active position opposite the web 5 by operation of the positioning motor PM under control by the motor control system PMC. When the paster components are thus positioned for splicing, a contact A2 closes for purposes explained below. The brush B and the knife K, when set to the proper position, are spring loaded. They are tripped at the proper moment by a brush trip solenoid BTS connected to a trip control system BTC, and by a knife trip solenoid KTS under control by components shown schematically at KTC.

It should be understood that the printing-press and reel-stand assembly shown in FIG. 2 and described above is known as such and conventional, with the exception of the fact that two tachometers PRT and SPT are provided on the printing press and on the roll spindle respectively. However, the known components of the system are controlled in a novel manner from both tachometers and for this purpose are interconnected as described presently with reference to the circuit diagram shown in FIG. 3.

The control system is energized from an alternatingcnrrent three-phase line 21. The above-mentioned reel rotation motor RM is energized from line 21 under control by a forward contactor FWD and a reverse conta'ctor REV whose respective coils are denoted by 22 and 23.

The two contactors are electrically interlocked. The reverse contactor can be operated at will by closing a push-button contact 24. The forward contactor FWD can be operated at will by closing a push-button contact 24a, or it can be operated automatically. The forward contactor FWD, when active, causes the reel rotation motor RM to rotate the spindle assembly 2 (FIG. 2) clockwise into active position.

Excitation for coils 22 and 23 is supplied from the alternatingcurrent line 21 through a transformer 25 and leads 28a, 2% under control by push-button switches 24 and 24a which permit manual control of reel rotation. A paster on-off switch 26 and a normally closed re-set contact 27 connect transformer 25 with control leads 28, 29. Closing of switch 26 renders the control system operative for automatic operation.

The coil 22 of contactor FWD and several other relays described below receive voltage from leads 28, 29, under control by a push-button switch AUTO and a lockin relay AR whose coil 30 controls a normally open contact 31. For initiating a paster operation, the attendant merely depresses the AUTO button whereafter the relay AR closes its contact 31 and then remains sealed in. Thereafter the relay AR will drop ofi only when the reset contact 27 is opened by hand or when the on-off switch 26 is opened. The operative condition of the relay system is indicated by a signal lamp 32.

The system further comprises a lock-out relay RR whose coil as controls three normally open contacts 41, 42, 43. Coil 49 is energized from leads 28a, 29a, under control by a switch A1 which is closed only when the printing press is running at a speed above a given minimum below which paster action is not desirable. Contact A1 prevents any paster operation under unsuitable operating conditions. During the entire normal operation described hereinafter, the relay RR is continuously picked up and the contacts 41 to 43 remain closed.

A transfer relay DT has its control coil 56 energized from leads 28, 29 through the contact 42 of relay RR, as Well as by the above-mentioned contact A2 of the brush and knife assembly. As mentioned, the contact A2 closes when the splicer assembly is placed into active position by the positioning motor PM. Relay DT has four contacts 51, 52, 53, 54.

The control unit PMC for the pneumatic or electric positioning drive PM, which as mentioned, also controls the lowering of the accelerating drive, is controlled by contact 54 of relay DT and by the contact 63 of another relay FR whose coil 60 also controls two other contacts 61, 62. The accelerating drive control ADC for operating the accelerating motor AM is shown, for simplicit to be connected in parallel to the control unit PMC, it being understood that the unit ADC will commence operating with delay, namely after the accelerating drive is lowered to the proper operating position. A limit contact A2 which may be associated and operated together with contact A2, disconnects the control unit PMC when the brush and knife assembly have reached the proper operating position.

The control units ETC and KTC for the respective brush trip solenoid BTS and knife trip solenoid KTS are controlled in time sequence by the contact 62 of relay PR and by the contact 72 of another relay FT whose coil 7 i also controls a contact 71.

The above-mentioned two tachometers PRT and SPT energize the respective coils ZDR and TDR of a diiferential relay DR which has two contacts 81 and 82. Coil 1BR is connected to the positive and negative terminals of the spindle tachometer SPT under control by contact 4-1 of relay RR and in series with an adjustable resistor R1. Coil ZDR is connected with the positive and negativ terminals of the press tachometer PRT through two parallel resistance branches of which only one is active at a time under control by respective contacts 51, 52, of relay DT. The first branch comprises resistors R2A and R28. The second branch comprises resistors R3, R4A and R43. A valve-action rectifier RC is connected in parallel relation to tachometer PRT and in series with resistor R3. The rectifier RC is poled for forward conductance and is inactive as long as the voltage E of the tachometer PRT is below a given threshold value and is adjustable by means of resistor R3. As long as the tachometer voltage is below the adjusted value, this voltage is edective to pass a proportional current through coil ZDR, whose current magnitude can be adjusted by means of resistors R413 or R23, but when the voltage E of tachometer PRT exceeds the predetermined value, current commences to flow through rectifier RC thus limiting the current passing through the coil 'ZDR.

The operation of the system is as follows.

Assume that the printing press is running and that the rolls on the reel stand are in the position illustrated (FIG. 2). For initiating a paster operation the attendant depresses the AUTO button well in advance of the time when paster operation is required. This merely prepares the control system for subsequent automatic operation. The reel does not yet rotate to the next position as long as the diameter of the expiring roll has not decreased to the proper diameter. Closing of the AUTO button energizes the relay AR which seals itself in at contact 33. and thus maintains the control system ready for operation. As thereafter the roll 3 (FIG. 2) expires, the current i in coil TDR of difierential relay DR increases. When current I exceeds the current E in coil 233R by a small value Al, the relay DR transfers. Its contact 8?. now energizes coil or? of relay FR which closes its contact 63 and thereby initiates the first portion of the paster cycle by energizing the control units PMC, ADC and relay CR1 in timed sequence. The coil 22 of contactor FWD is energized and the reel rotation motor RM becomes active to place the new roll 4 into proper position. When that position is reached, the photoelectric cell 16 causes actuation of a relay CR2 which deenergizes coil 22 and thus stops the reel rotation motor RM. The accelerating drive is then lowered into engagement with the new roll 4 and then actuated by motor AM, and the brush and nnife assembly is placed into active position. When this is completed, the contact A2 closes so that relay DT will pick up. This trans ers the voltage of tachometer PRT from resistance branch R3, R4A, R43, to branch RZA, R218. The resistance of resistors RZA and RZB is such that the current I is reduced with the result that the differential relay DR returns to its original, illustrated position. Consequently the coil so of relay FR is now deenergized by the opening of contact 81, while relay FT picks up due to closing of contact 53.

As now the roll 3 continues to expire, a point will be reached where relay DR again transfers and thus energizes the coil 64 by closing of contact 31. Relay FR picks up and closes its contact 62. Since contact 72 of relay PT is closed at that time, the control units ETC and KTC are energized thus tripping the solenoids BTS and KTS in timed sequence.

All components are re-set to the original condition when relays DR and DT become deenergized.

The above-described control system can readily be set to operate substantially in accordance with the ideal performance typified by curve A in PEG. 1, as will be explained presently.

If E is the voltage of the spindle tachometer SPT, E the voltage of the press reference tachometer PRT, and S the linear speed of the expiring web passing into the printing press, then E =K S, where K is a constant, and E =K S/ d, where K is a constant and d is the diameter of the expiring roll. Consequently: d=K S/E and S=E /K or:

wherein K (K =K /K is a cons-taut.

It follows that the diameter of the expiring roll is proportional to the ratio of E to E The relay DR is sumciently sensitive to transfer from one to its other condition when the current i produced trol is a modifying effect which increases at increasing press speed to progressively reduce the critical diameter below the one at which the ratio detector would otherwise respond. This modifying etfect is produced by the limitation in voltage and current which the rectifier RC imposes upon the AE -responsive circuit of the ratio detector relay. That is, at low values of E the current flowing through coil 2BR is proportional to voltage E but when the voltage drop across rectifier ER exceeds the threshold value, part of the current driven by voltage E is shunted through the rectifier, thus reducing and H limiting the current I in coil 2BR. Thus the voltage impressed across coil 2BR of relay DR has essentially the characteristic apparent from FIG. 4 where the curve :1 indicates the voltage curve as it would obtain if rectifier R were not used, While curbe b denotes the modified voltage curve. Due to the fact that the voltage of coil ZDR remains approximately constant at high press speeds while no limitation is imposed upon the share of the pilot voltage at coil lDR, the reference-to'pilot voltage ratio at Which the relay DR will transfer decreases toward higher press speed. Consequently, the performance departs from the pure-ratio curve B in FIG. 1 toward smaller critical roll diameters with increasing press speeds. As a result, the ideal performance according to curve A in Fl. 1 can be closely approached or virtually realiwed to the full extent.

Turning now to the modifications schematically illustrated in FIGS. 5 to it should be understood that each of them concerns only the ratio-detector or differential-relay network, corresponding to the one shown in heavy lines at the upper left of FIG. 3. The reference characters in FIGS. 5 to 10 are identical with those used in FIG. 3 for functionally analogous components re spectively. It should further be understood that, while FIG. 5 illustrates some auxiliary components such as the contacts 51, 52 of relay DT (FIG. 3) and the contact 41 of relay RR (FIG. 3), the circuit diagrams of FIGS. 6 to 10 are simplified by showing only the components that participate in the speed-ratio-responsive control operation.

The relay network of FIG. 5 differs from that of FIG. 3 essentially only in that the rectifier RC is a triodc. While an electronic tube is illustrated, it will be understood that a controlled semiconductor rectifier may be used instead. The triode increases its conductance or is triggered to become conductive as the reference voltage of the press tachometer PRT increases, the trigger voltage being taken from a potentiometer PT connected across the terminals of the tachometer PRT.

According to FIG. 6, the increase of the press tachometer voltage is used for transferring a control relay CR3 when a given voltage value is exceeded, with the efiect of inserting a resistor R5 in series with the coil 2BR of the difierential relay. Denoted by R11 and R12 are adjustable calibrating resistors.

The modification shown in FIG. 7 is similar to that of FIG. 6 except that a relay CR4, responsive to a given increase in press tachometer voltage, shorts a resistor R6 in series with the spindle tachometer SPT.

In each of the modifications so far described, the ratio of press tachometer voltage to spindle tachometer voltage is reduced as regards its effect upon the differential relay, when the press reference voltage exceeds a given value. Thus the ultimate effect is similar to that of the system shown in FIG. 3, although we consider the system of FIG. 3, using a semiconductor rectifier RC, to be preferable because it permits in a simple manner a more gradual and closer adaptation to the ideal performance curve as explained above with reference to FIGS. 1 and 4.

The desired differential effect can also be produced electrically so that a single-circuit relay rather than a differential relay may be used for response to the predetermined differential or ratio value of press tachometer voltage and spindle tachometer voltage. An embodiment of this kind is shown in FIG. 8. The differential effect is produced by means of two resistors R7 and R8 which are connected in voltage-opposed series relation to a control relay CR5. Relay CR5 takes the place of the relay DR in a system otherwise corresponding to that of FIG. 3 and picks up when the differential current (I -1 exceeds a given value. Denoted by R13 is a calibrating resistor.

According to FIG. 9 the coil ZDR of a differential relay corresponding to that described with reference to FIG. 3 is excited from a potentiometer PTl whose slide is displaced by an electromagnetic actuator AC1 in accordance with the voltage of the press tachometer PRT. The resistance graduation of potentiometer PTl is nonlinear so that the incremental increase in tapped-off voltage decreases with increasing press speed.

According to FIG. 10 a similar actuator device, responsive to the voltage of the spindle tachometer SPT, is used for increasing the incremental change in voltage of a potentiometer PT2 as the spindle tachometer voltage increases. In principle, devices of the type shown in FIGS. 9 and 10 also operate to make the control performance approach the desired ideal characteristic A in PEG. 1, although the necessary equipment is more complicated than that described with reference to PEG. 3.

It will be obvious to those skilled in the art, upon a study of this disclosure, that our invention permits of various modifications with respect to circuitry and components, and hence may be given embodiments other than particularly illustrated and described herein, without departing from the essential features of our invention and within the scope of the claims annexed hereto.

We claim:

1. An automatic paster control system for splicing a new roll to an expiring roll of paper being fed to a rotary printing press, comprising paster control means for releasing the splicing operation, a speed-responsive source of pilot voltage proportional to the rotating speed of the expiring roll, a speed-responsive source of reference voltage proportional to the press speed, ratio-sensing relay means having two electric input circuits connected to said respective voltage sources and having an output member responsive to occurrence of a datum value of the reference-to-pilot voltage ratio and controllingly connected to said paster control means for releasing the operation of the latter when responding to said value, and ratio-setting means connected with said source of reference voltage to be controlled in dependence upon the press speed, said setting means being operatively connected to one of said input circuits in the sense required for decreasing said ratio datum value with increasing reference voltage.

2. An automatic paster control system for splicing a new roll to an expiring roll of paper being fed to a rotary printing press, comprising paster control means for releasing the splicing operation, a speed-responsive source of pilot voltage proportional to the rotating speed of the expiring roll, a speed-responsive source of reference voltage proportional to the press speed, differential relay means having two opposingly active relay control circuits connected to said respective two voltage sources and having a relay-output circuit controlled in response to occurrence of a given slight value of differential relay excitation of said two controlling circuits, circuit means connecting said relay output circuit with said paster control means to cause operation of the latter when said relay means respond to said value, and voltage-responsive excitation control means connected with said source of reference voltage to be controlled by said reference voltage, said excitation control means being in controlling connection with one of said relay control circuits and adapted to decrease the ratio of reference-voltage excitation to pilot-voltage excitation of said relay means with increasing reference voltage.

3. An automatic paster control system for splicing a new roll to an expiring roll of paper being fed to a rotary printing press, comprising paster control means for releasing the splicing operation, a speed-responsive source of pilot voltage proportional to the rotating speed of the expiring roll, a speed-responsive source of reference voltage proportional to the press speed, differential relay means having two opposingly active relay control circuits connected to said respective two voltage sources and having a relay-output circuit controlled in response to occurrence of a given slight value of differential relay excitation of said two controlling circuits, circuit means connecting said relay output circuit with said paster control means to cause operation of the latter when said relay means respond to said value, a normally inactive bypass circuit connected across said reference voltage source and conductive in dependence upon said reference voltage exceeding a given minimum value, whereby the ratio of reference-voltage excitation to pilot-voltage excitation of said relay means is progressively decreased as said reference voltage increases beyond said minimum value.

4. An automatic paster control system for splicing a new roll to an expiring roll of paper being fed to a rotary printing press, comprising paster control means for releasing the splicing operation, a speed-responsive source of pilot voltage proportional to the rotating speed of the expiring roll, a speed-responsive source of reference volt age proportional to the press speed, ratio-sensing relay means having two electric input circuits connected to said respective voltage sources and having an output member responsive to occurrence of a datum value of the refence-to-pilot voltage ratio and controllingly connected to said paster control means for releasing the operation of the latter when responding to said value, a valve-action rectifier connected across said reference voltage source with the poling required for decreasing said ratio datum value when said reference voltage increases beyond a given threshold value.

5. In a printing plant comprising a rotary printing press, a roll stand having a plurality of spindle means for accommodating respective rolls of paper to be sequentially fed to the press, and web splicing means for attaching the web of a new roll to the web of an expiring roll on said stand, the combination of an electric system for controlling said splicing means to make the splice during continuous operation of the press, said system comprising a spindle tachometer on said stand for providing a pilot voltage proportional to the rotating speed of the expiring roll, a reference tachometer on said press for providing a reference voltage proportional to the speed of the press, a differential electromagnetic relay having two opposingly interrelated relay coils of which one is connected to said reference tachometer and t e other to said spindle tachometer, whereby said relay is responsive to occurrence of a given difference of the currents flowing from said tachometers through said respective coils, a valve-action rectifier connected parallel to said reference tachometer and poled for limiting the current in said one coil when said reference voltage exceeds a given threshold value, and tripcontrol means connecting said relay with said splicing means for tripping said splicing means to make the splice when said relay responds.

6. A system for controlling the automatic paster assembly of a rotary printing press to effect splicing of a new roll to an expiring roll of paper fed to the press, comprising positioning means for placing the paster assembly to ready position, trip-control means for releasing the paster assembly to perform the splicing operation, a speed-responsive source of pilot voltage proportional to the rotating speed of the expiring roll, a speed-responsive source of reference voltage proportional to the press speed, ratio-sensing relay means having two electric input circuits connected to said respective voltage sources and having an output member responsive to occurrence of a datum value of the reference-to-pilot voltage ratio, switch means having two sequential switching conditions and connecting in the first one of said conditions said relay output member with said positioning means for controlling said positioning means to place said paster assembly in ready position in response to occurrence of said ratio datum value, said positioning means having a control contact actuable only when said assembly is in said ready position, said control contact being connected with said switch means for placing it in second switching condition when said assembly reaches said ready position, first ratio-setting means controlled by said contact and electrically connected with one of said relay input circuits for decreasing said ratio datum value a given amount in dependence upon actuation of said control contact whereby said relay means are returned to original condition when said switch means are in second switching condition, second ratiosetting means connected with said source of reference voltage to be controlled in dependence upon the press speed, said setting means being operatively connected to one of said input circuits in the sense required for decreasing said ratio datum value with increasing reference voltage, and means connecting said relay output member with said trip-control means only when said switch means is in said second switching condition whereby said paster assembly, when in ready position, is released for splicing operation by the second response of said relay means.

7. An automatic paster control system for splicing a new roll to an expiring roll of paper being fed to a rotary printing press, comprising paster control means for releasing the splicing operation, a speed-responsive source of pilot voltage proportional to the rotating speed of the expiring roll, a speed-responsive source of reference volt age proportional to the press speed, a differential relay having two opposingly active control coils of which one is connected to said pilot-voltage source, two parallel resistive circuit branches connecting said other coil with said reference-voltage source and including interlock switch means so that only one of said respective circuit branches is active at a time, said two branches having respectively different resistances thus impressing upon said other relay coil respectively difierent shares of said reference voltage under control by said switch means, said paster control means comprising positioning means for preparing the splicing operation and trip means for completing the splicing operation, said positioning means being connected with and controlled by said relay when said relay picks up in response to a given difierential excitation from said two sources while one of said branches is active, and said positioning means being controllingly connected with said switch means for switching the latter over to said other branch when the preparation of the splicing operation is terminated, whereby said relay is caused to drop oif and to thereafter pick up a second time in response to recurrence of said given diiferential excitation dueto increase of said reference voltage, and circuit means connecting said relay with said trip means 11 12 only when said switch means is in switched-over condisaid rectifier being poled for conducting current when said tion, whereby the splicing operation is completed under reference voltage exceeds a given value. control by the second response of said differential relay.

8. A paster control system according to claim 7, c-om- Reffil'fllces Ciiefl in the file 0f this Patent prising a valve-action rectifier connected in parallel to 5 FOREIGN PATENTS said reference-voltage source and in series with part of the resistance of the secondactive parallel circuit branch, 684765 Great Britain 1952 

